Bnns / metal mesh laminated transparent heater and preparation method thereof

Abstract

The present application relates to a kind of BNNSs / metal grid laminated transparent heater and its preparation method, by mixing hexagonal boron nitride powder with polar solvent is carried out water bath ultrasonic treatment, after centrifugation, obtain hexagonal boron nitride nanosheet dispersion liquid;Metal nanowire solution is laid on transparent substrate, and metal nanowire transparent substrate is obtained after drying;Edge of metal nanowire transparent substrate is coated with electrode material;Hexagonal boron nitride nanosheet is deposited on metal nanowire grid transparent substrate using electrophoretic deposition process, so that hexagonal boron nitride nanosheet is wrapped in metal grid layer.The method is hydroxylated by water bath ultrasonic and electrodeposition process, the surface of hexagonal boron nitride is modified, the surface potential is enhanced, the binding force between it and polar molecule is increased, so that BNNSs is coated on the surface of metal nanowire, the heater obtained by the method has good uniformity and optical transparency, and has good stability in high-temperature and humid environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of transparent heater, in particular to a BNNSs / metal mesh laminated transparent heater and a preparation method thereof. BACKGROUND

[0002] The transparent heater is a kind of transparent device that converts electrical energy into heat energy by Joule effect. Its high heating efficiency and high light transmittance make it have a huge market in the applications of defogging and deicing of smart glass, thermal chromic, etc. Under this background, silver nanowire transparent heater has been widely studied in recent years. Compared with many alternative materials of transparent conductive oxide, silver is abundant in reserves, and silver nanowire mesh has great application potential in transparent heater due to its high electrical conductivity, flexibility and good light transmittance.

[0003] The silver nanowire transparent heater is prepared by a large number of short silver nanowire free joints to form a thin film with good electrical conductivity, and the nodes formed by the joints are used for energy conversion. These nodes often have a larger contact resistance, and when an electric current passes through, more heat is generated at these nodes. When a large amount of heat is concentrated at the nodes with a very small contact area, the instantaneous high temperature will quickly melt the nanowire, affecting the performance of the overall thin film. In addition, the large specific surface area of silver nanowire makes it easy to oxidize and even break in a high-temperature, high-humidity and oxygen-rich environment, making it difficult to work stably for a long time. The existing introduction of carbon-based nanomaterials into the AgNWs mesh greatly reduces the light transmittance of the device. SUMMARY

[0004] In view of the technical problems existing in the prior art, the primary object of the present application is to provide a BNNSs / metal mesh laminated transparent heater and a preparation method and application thereof. Hexagonal boron nitride is a wide bandgap material with good optical transmittance, and also has good thermal conductivity and very high stability, oxidation resistance and corrosion resistance, which is an ideal protective material. The h-BN powder is peeled off by ultrasonic assisted hydrolysis, the chemical bonds between the layers and even within the layers of the h-BN powder are broken by the cavitation effect of ultrasonic waves, which causes the BNNSs nanosheets to be peeled off from the powder and the lateral size to be reduced. The exposed boron radicals at the edges and defects of the BNNSs combine with the hydroxyl groups generated by the splitting of water molecules, resulting in many polar hydroxyl hanging bonds. On the one hand, the BNNSs become easy to combine with water molecules to form a uniform and stable dispersion liquid, and on the other hand, the surface potential of the BNNSs is increased, so that the electrophoretic deposition process successfully wraps the BNNSs material on the surface of the metal nanowire mesh, which is in close contact with the metal mesh, avoids pollution of the exposed area of the substrate, and better adheres to the surface of the metal mesh. This feature is very friendly to the optical transmittance of the transparent heater.

[0005] The present application at least adopts the following technical solutions:

[0006] The application provides a preparation method of a BNNSs / metal mesh laminated transparent heater.

[0007] The hexagonal boron nitride powder is mixed with deionized water and subjected to water bath ultrasonic treatment, and then centrifuged to obtain a hexagonal boron nitride nanosheet dispersion solution.

[0008] The metal nanowire solution is laid on the transparent substrate, and a metal nanowire transparent substrate is obtained after drying.

[0009] An electrode material is coated on the edge of the metal nanowire transparent substrate, and a metal nanowire mesh transparent substrate is obtained after low-temperature drying.

[0010] The hexagonal boron nitride nanosheet is deposited on the metal nanowire mesh transparent substrate by an electrophoretic deposition process, so that the hexagonal boron nitride nanosheet wraps the metal mesh layer, and the BNNSs / metal mesh laminated transparent heater is obtained after low-temperature drying.

[0011] Further, the mass-volume ratio of the hexagonal boron nitride powder to deionized water is (40-50) mg:(20-25) ml; in the electrophoretic deposition process, the metal nanowire mesh transparent substrate serves as a cathode, the deposition voltage is 10-20 V, and the deposition time is 10-25 min.

[0012] Further, the metal nanowire solution is selected from gold, silver or copper nanowire solution, the water bath ultrasonic treatment time is not less than 8 h, the centrifugal speed is 3000-3500 r / min, and the centrifugal time is 5-30 min.

[0013] Further, the metal nanowire solution is selected from silver nanowire solution.

[0014] Further, the deposition voltage is 10-16 V, and the deposition time is 20-25 min.

[0015] Further, the metal nanowire solution is laid on the transparent substrate by spin coating, drop coating, spraying or Meyer rod method.

[0016] Another aspect of the application also provides a BNNSs / metal mesh laminated transparent heater, which comprises a transparent substrate, a metal nanowire mesh layer laid on the surface of the transparent substrate, an electrode material arranged at the edge of the metal nanowire mesh layer, a hexagonal boron nitride nanosheet layer wrapping the metal nanowire mesh layer, and the hexagonal boron nitride nanosheet layer wrapping the metal nanowire mesh layer by an electrodeposition process.

[0017] Further, the material of the metal nanowire mesh is selected from gold, silver or copper.

[0018] Further, the optical transmittance of the stacked transparent heater is within 5% of that of a pure metal mesh transparent heater.

[0019] Another aspect of the present application also relates to the application of the above-mentioned BNNSs / metal mesh stacked transparent heater in the fields of screens, electrodes, glasses, electronic curtains, windows, lampshades, and flexible electronic skins.

[0020] The preparation method of the present application combines water bath ultrasonic treatment with electrophoretic deposition process, reduces the lateral size of BNNSs, and combines the exposed boron radicals at the edges and defects of BNNSs with the hydroxyl groups generated by the cleavage of water molecules. The polar hydroxyl dangling bonds that appear make BNNSs easily combine with water molecules to form a uniform and stable dispersion liquid. On the other hand, the surface potential of BNNSs is increased, so that BNNSs are uniformly deposited on the surface of the metal nanowire mesh in the electrophoretic deposition process, and the metal nanowire mesh is coated, which improves the stability of the heater, avoids pollution to the exposed area of the substrate, and improves the optical transmittance of the transparent heater. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 Fig. (a) is a TEM image of the BNNSs dispersion of Example 1; Fig. (b) is an HR-TEM image of the BNNSs, and the upper right corner inset is an electron diffraction pattern; Fig. (c) is a Raman characterization of the h-BN powder before exfoliation and the BNNSs after exfoliation; and Fig. (d) is a uniform BNNSs dispersion that is left standing at room temperature for 7 days.

[0022] Figure 2 Fig. (a) is a time-temperature response curve of the heater obtained in Comparative Example 1, and the inset is a thermal imaging picture at a voltage of 5 V, and Fig. (d) is an SEM morphology picture thereof; Fig. (b) is a time-temperature response curve of the heater obtained in Comparative Example 2, and the inset is a thermal imaging picture at a voltage of 5 V, and Fig. (e) is an SEM morphology picture thereof; Fig. (c) is a time-temperature response curve of the heater obtained in Example 1, and the inset is a thermal imaging picture at a voltage of 5 V, and Fig. (f) is an SEM morphology picture thereof.

[0023] Figure 3 Fig. is a graph of the optical transmittance change of the heaters of Comparative Example 1 and Example 1 and Comparative Example 3.

[0024] Figure 4 Fig. is an SEM morphology picture of the heaters of Comparative Example 1 and Example 1 under different environments.

[0025] Figure 5 Fig. is a time-temperature response curve of the heaters of Example 1 and Comparative Example 1 at a driving voltage of 4 V after being placed in a high-temperature and high-humidity environment at 85°C for 10 days.

[0026] Figure 6SEM topography of the heater at different voltages in Example 3.

[0027] Figure 7 Optical transmittance of the heater at different voltages in Example 3. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings of the present application. The described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application. In the following examples, the experimental methods are conventional methods unless otherwise specified, and the reagents and materials are commercially available unless otherwise specified.

[0029] Spatially relative terms such as "beneath", "below", "lower", "above", "upper", and the like, are used herein for ease of description to explain the positioning of one element relative to a second element. The terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures.

[0030] In addition, terms such as "first", "second", and the like, are used to describe various elements, layers, regions, sections, etc. and are not intended to be limiting. "Have", "have", "contain", "include", and the like are open terms, indicating the presence of the stated component or feature, but not excluding additional components or features. Unless the context clearly dictates otherwise.

[0031] The present application provides a BNNSs / metal mesh laminated transparent heater, which comprises a transparent substrate, and the material of the transparent substrate includes but is not limited to quartz glass, PET, PVA, PI, etc. In a preferred embodiment, the material of the transparent substrate is selected from quartz glass.

[0032] The surface of the transparent substrate is paved with a metal nanowire mesh layer, and the metal nanowire includes but is not limited to gold, silver, copper, etc. In a preferred embodiment, the metal nanowire is selected from silver nanowire, and the diameter D of the silver nanowire is 28-30 nm, and the length L is 10-20 μm. The silver nanowire is dispersed in isopropyl alcohol to form a silver nanowire solution. In a preferred embodiment, the concentration of the silver nanowire solution is 0.25 wt%. The silver nanowire solution is paved on the transparent substrate by spin coating process, and then dried at low temperature in an inert gas environment to obtain a silver nanowire mesh layer.

[0033] The edge of the metal nanowire mesh layer is provided with an electrode material, and the electrode material is selected from silver or copper. Hexagonal boron nitride nanosheets are arranged on a transparent substrate and wrap the metal nanowire mesh layer. The electrophoretic deposition process is used to deposit the hexagonal boron nitride nanosheet layer on the metal nanowire mesh transparent substrate, so that the hexagonal boron nitride nanosheet wraps the metal mesh layer.

[0034] Before the electrophoretic deposition process, the h-BN powder is mixed with deionized water and subjected to water bath ultrasonic treatment, and then centrifuged, and the supernatant is taken to obtain a BNNSs nanosheet dispersion. ITO conductive glass is selected as a conductive anode, and the above metal nanowire transparent substrate is selected as a cathode, and the two are placed at a certain distance in the BNNSs nanosheet dispersion, and a voltage of 10-20V is applied, and the electrophoretic deposition is carried out for 10-25min, and then it is fished out and dried at low temperature.

[0035] Example 1

[0036] A certain volume of silver nanowire solution dispersed in IPA (isopropyl alcohol) and isopropyl alcohol are prepared, the concentration of the silver nanowire solution is 1wt%, the diameter D of the silver nanowire is 28-30nm, and the length L is 10-20μm, then the silver nanowire solution is dispersed in isopropyl alcohol, the volume ratio of the silver nanowire solution to isopropyl alcohol is 1:4, then the silver nanowire slurry with a concentration of about 0.25wt% is obtained after ultrasonic treatment for 5min, and the silver nanowire slurry is spread on a clean quartz sheet using a spin coating machine to form an AgNWs film, the rotation speed of the spin coating machine is 3500r / min, the spin coating time is 60s, and the size of the quartz sheet is 1.5*1.5cm, and the amount of silver nanowire slurry on each quartz sheet is about 80μL. Then anneal at 60℃ for 10min; then the conductive silver paste is coated on the edges of both sides of the AgNWs film, and the quartz sheet is placed in an inert gas environment for low-temperature drying to obtain a silver nanowire mesh transparent substrate.

[0037] Then, 40mg of hexagonal boron nitride (h-BN) powder with a particle size of 22μm is dispersed in 20mL of deionized water, and the slurry is subjected to water bath ultrasonic treatment for 8h, and then centrifuged at 3500r / min for 5min, and the supernatant is collected to obtain a h-BN nanosheet dispersion. The morphology of the obtained BNNSs dispersion is tested, as shown in Figure 1Fig. (a) is a TEM image of the obtained BNNSs dispersion, the lateral size of which is about 1.4 μm, which is reduced compared to the original lateral size of 22 μm, which is consistent with the expected effect; Fig. (b) is a HR-TEM image of the BNNSs, and the inset in the upper right corner is an electron diffraction pattern, which proves that the prepared BNNSs have good crystallinity; Fig. (c) is a Raman characterization of the h-BN powder before exfoliation and the BNNSs after exfoliation, the characteristic peaks of the BNNSs after exfoliation are red-shifted, the half-peak width of the E2g vibration mode is widened, and the intensity is also significantly reduced, which indicates that the interlayer interaction of the boron nitride nanosheet is weakened, and the sheet layer is thinned; Fig. (d) is a uniform BNNSs dispersion that has been standing at room temperature for 7 days, the bottle on the left in the figure is a right-side-up appearance, and the bottle on the right is an upside-down appearance. The h-BN nanosheet dispersion obtained by the method has good uniformity.

[0038] Subsequently, a direct current power source was prepared, ITO conductive glass was used as an anode, and the above silver nanowire grid transparent substrate was used as a cathode, the conductive surfaces of the anode and the cathode were opposite to each other, the distance between the anode and the cathode was 1.5 cm, the anode and the cathode were placed in the h-BN nanosheet dispersion, a voltage of 12 V was applied, and after 20 min of deposition, the anode and the cathode were taken out, and then low-temperature drying was performed at 60 °C for 10 min.

[0039] Example 2

[0040] A silver nanowire solution dispersed in IPA (isopropyl alcohol) and isopropyl alcohol were prepared, the concentration of the silver nanowire solution was 1 wt%, the diameter D of the silver nanowire was 28-30 nm, and the length L of the silver nanowire was 10-20 μm, then the silver nanowire solution was dispersed in isopropyl alcohol, the volume ratio of the silver nanowire solution to isopropyl alcohol was 1:4, then a silver nanowire slurry with a concentration of about 0.25 wt% was obtained after ultrasonic treatment for 5 min, a spin coating machine was used to dynamically spin coat the silver nanowire slurry on a clean quartz sheet to form an AgNWs film, the rotation speed of the spin coating machine was 3000 r / min, the spin coating time was 80 s, the size of the quartz sheet was 1.5*1.5 cm, and the amount of silver nanowire slurry on each quartz sheet was about 60 μL, then low-temperature drying was performed at 60 °C for 10 min.

[0041] Then, the conductive silver paste was coated on the edges of both sides of the AgNWs film, and the quartz sheet was placed in an inert gas environment for low-temperature drying to obtain a silver nanowire grid transparent substrate.

[0042] Then, 50 mg of hexagonal boron nitride (h-BN) powder with a particle size of 22 μm was dispersed in 25 mL of deionized water, and water bath ultrasonic treatment was performed for 8 h, then the obtained slurry was centrifuged at 3000 r / min for 5 min, and the supernatant was collected to obtain a h-BN nanosheet dispersion.

[0043] Subsequently, a direct current power supply was prepared, ITO conductive glass was used as an anode, and the above silver nanowire grid transparent substrate was used as a cathode. The conductive surfaces of the anode and the cathode were opposite to each other, and the distance between them was 2 cm. The anode and the cathode were placed in the h-BN nanosheet dispersion liquid, a voltage of 16 V was applied, and after 20 min, the anode and the cathode were taken out. Subsequently, low-temperature drying was performed at 60°C for 10 min.

[0044] Example 3

[0045] A silver nanowire solution with a concentration of 1 wt% and isopropanol were prepared, and the silver nanowire solution was dispersed in isopropanol. The diameter D of the silver nanowire was 28-30 nm, and the length L of the silver nanowire was 10-20 μm. Subsequently, the silver nanowire solution was dispersed in isopropanol, and the volume ratio of the silver nanowire solution to isopropanol was 1:4. After ultrasonic treatment for 5 min, a silver nanowire slurry with a concentration of about 0.25 wt% was obtained. A spin coating machine was used for dynamic spin coating, and the silver nanowire slurry was spread on a clean quartz sheet to form an AgNWs film. The rotation speed of the spin coating machine was 3500 r / min, the spin coating time was 60 s, the size of the quartz sheet was 1.5*1.5 cm, and the amount of silver nanowire slurry on each quartz sheet was about 80 μL. Subsequently, annealing was performed at 80°C for 10 min. Then, conductive silver paste was applied to the edges of both sides of the AgNWs film. The quartz sheet was placed in an inert gas environment for low-temperature drying to obtain a silver nanowire grid transparent substrate.

[0046] Subsequently, 40 mg of hexagonal boron nitride (h-BN) powder with a particle size of 22 μm was dispersed in 20 mL of deionized water, and water bath ultrasonic treatment was performed for 8 h. The obtained slurry was centrifuged at 3500 r / min for 5 min, and the supernatant was collected to obtain an h-BN nanosheet dispersion liquid.

[0047] Subsequently, a direct current power supply was prepared, ITO conductive glass was used as an anode, and the above silver nanowire grid transparent substrate was used as a cathode. The conductive surfaces of the anode and the cathode were opposite to each other, and the distance between them was 2 cm. The anode and the cathode were placed in the h-BN nanosheet dispersion liquid, a voltage of 16 V was applied, and after 20 min, the anode and the cathode were taken out. Subsequently, low-temperature drying was performed at 60°C for 10 min.

[0048] Comparative Example 1

[0049] A certain volume of silver nanowire solution dispersed in IPA (isopropyl alcohol) and isopropyl alcohol were prepared, the concentration of the silver nanowire solution was 1wt%, the diameter D of the silver nanowire was 28-30nm, and the length L of the silver nanowire was 10-20μm, then the silver nanowire solution was dispersed in isopropyl alcohol, the volume ratio of the silver nanowire solution to isopropyl alcohol was 1:4, then a silver nanowire slurry with a concentration of about 0.25wt% was obtained after ultrasonic treatment for 5min, a dynamic spin coating was performed using a spin coating machine, the silver nanowire slurry was spread on a clean quartz sheet to form an AgNWs film, the rotation speed of the spin coating machine was 3000r / min, the spin coating time was 80s, the size of the quartz sheet was 1.5*1.5cm, and the amount of silver nanowire slurry on each quartz sheet was about 60μL, then low-temperature drying was performed at 60℃ for 10min.

[0050] Then, conductive silver paste was applied to the edges of both sides of the AgNWs film, and the quartz sheet was placed in an inert gas environment for low-temperature drying to obtain a silver nanowire grid transparent substrate heater.

[0051] Comparative Example 2

[0052] A certain volume of silver nanowire solution dispersed in IPA (isopropyl alcohol) and isopropyl alcohol were prepared, the concentration of the silver nanowire solution was 1wt%, the diameter D of the silver nanowire was 28-30nm, and the length L of the silver nanowire was 10-20μm, then the silver nanowire solution was dispersed in isopropyl alcohol, the volume ratio of the silver nanowire solution to isopropyl alcohol was 1:4, then a silver nanowire slurry with a concentration of about 0.25wt% was obtained after ultrasonic treatment for 5min, a dynamic spin coating was performed using a spin coating machine, the silver nanowire slurry was spread on a clean quartz sheet to form an AgNWs film, the rotation speed of the spin coating machine was 3000r / min, the spin coating time was 80s, the size of the quartz sheet was 1.5*1.5cm, and the amount of silver nanowire slurry on each quartz sheet was about 60μL, then low-temperature drying was performed at 60℃ for 10min.

[0053] Then, conductive silver paste was applied to the edges of both sides of the AgNWs film, and the quartz sheet was placed in an inert gas environment for low-temperature drying to obtain a silver nanowire grid transparent substrate.

[0054] Then, 50mg of hexagonal boron nitride (h-BN) powder with a particle size of 22μm was dispersed in 25mL of deionized water, and ultrasonic treatment was performed in a water bath for 8h, then the obtained slurry was centrifuged at 3000r / min for 5min, and the supernatant was collected to obtain a h-BN nanosheet dispersion.

[0055] The silver nanowire mesh transparent substrate prepared above was placed on a spin coating machine and the film was sucked. 60-80 μL of the BNNSs aqueous dispersion obtained in the first step was added dropwise to the surface of the device using a pipette, and the solution was spread at a speed of 3500 r / min. In view of the disadvantages of solvent concentration and waste of a large amount of solution caused by spin coating, the device was spin coated several times as appropriate to enhance the performance of the device. Then the device was heated at 60°C for 10 min to dry at low temperature, and the BNNSs / AgNWs laminated transparent heater prepared by spin coating process was obtained.

[0056] Comparative Example 3

[0057] A certain volume of silver nanowire solution dispersed in IPA (isopropanol) and isopropanol were prepared, the concentration of the silver nanowire solution was 1 wt%, the diameter D of the silver nanowire was 28-30 nm, and the length L was 10-20 μm. Then the silver nanowire solution was dispersed in isopropanol, the volume ratio of the silver nanowire solution to isopropanol was 1:4, and then a silver nanowire slurry with a concentration of about 0.25 wt% was obtained after ultrasonic treatment for 5 min. The silver nanowire slurry was spread on a clean quartz sheet using a spin coating machine to form an AgNWs film, the speed of the spin coating machine was 3000 r / min, the spin coating time was 80 s, the size of the quartz sheet was 1.5*1.5 cm, and the amount of silver nanowire slurry on each quartz sheet was about 60 μL. Then the quartz sheet was heated at 60°C for 10 min.

[0058] Then, the conductive silver paste was coated on the edges of both sides of the AgNWs film, and the quartz sheet was placed in an inert gas environment for low temperature drying to obtain a silver nanowire mesh transparent substrate.

[0059] Then, 20 mg of graphene powder was blended with 20 mL of deionized water, and treated by ultrasonic oscillation at 100 W for 8 hours to obtain a graphene aqueous dispersion.

[0060] The above prepared graphene aqueous dispersion was poured into a container, ITO conductive glass was used as an anode, and the above silver nanowire mesh transparent substrate was used as a cathode. The anode and the cathode were placed in the graphene aqueous dispersion with the conductive surfaces facing each other and a distance of 1.5 cm. A voltage of 10 V was applied, and the cathode was taken out after 20 min of deposition. The surface was gently washed with deionized water, and the water was absorbed with filter paper on the side. The Graphene / AgNWs laminated device was obtained by heating at 60°C for 10 min at low temperature.

[0061] The transparent heaters obtained in Example 1 and Comparative Example above were tested for performance, as follows: Figure 2Figures (a), (b) and (c) are time-temperature response curves of the pure silver nanowire film, the BNNSs / AgNWs stacked transparent heater prepared by spin coating and the BNNSs / AgNWs stacked transparent heater prepared by electrodeposition, respectively, under an excitation voltage of 3-5V; the inset is a thermal imaging picture at a voltage of 5V;

[0062] As can be seen from the thermal images and the time-temperature response curves, when the direct current excitation voltage is 3-4V, the steady-state temperature increases accordingly, and there is no obvious difference in the heating effect of the three. When the excitation voltage rises to 5V, the temperature of the pure AgNWs film rises sharply, the heat distribution is extremely uneven, and the area of the high-temperature region of the infrared thermal image rapidly decreases, indicating that the film has been fused in a large area. The transparent heater prepared by spin coating has similar heating performance to the pure AgNWs film, except that it maintains for a slightly longer time under an excitation voltage of 5V, proving that the introduction of BNNSs has improved the performance of the film to some extent, but due to the disadvantages of the small amount and uneven distribution of the nanosheets introduced by the spin coating method, it also cannot withstand high temperature and quickly fuses. The heater prepared by electrodeposition can maintain a temperature of about 50℃ under a voltage of 5V, and the current also remains stable, and the infrared thermal image is uniform and stable, proving that it has not fused in a large area. The BNNSs introduced by the electrodeposition method have a good protective effect on the silver nanowire grid, which can quickly spread the temperature at the junction to the surface of the film, making the whole film heat evenly and preventing local overheating from fusing.

[0063] (d) Figure, (e) Figure and (f) Figure are SEM microstructure characterization of pure silver nanowire film, BNNSs / AgNWs laminated transparent heater prepared by spin coating method and BNNSs / AgNWs laminated transparent heater prepared by electrodeposition method under scanning electron microscope, respectively. It can be seen that the pure silver nanowire film is smooth and clean on the surface, and a large number of contact nodes are formed at the overlapping place of nanowires. The device is exposed to air for a long time in the unprotected state, and the surface will be oxidized. The nodes are prone to breakage when the temperature is too high. The laminated device prepared by spin coating method can be directly observed that the nanosheet is transparent in single layer, which proves that the h-BN exfoliation effect is ideal. However, when BNNSs are introduced by spin coating method, it can be seen that there are more white spaces and uneven distribution of nanosheets on the surface of AgNWs film. BNNSs are randomly tiled on the surface of silver nanowires, and the probability of covering the nodes with serious heating is small, and the adhesion with nanowires is also poor, which is easy to be peeled off by external force. In Figure (f), each nanowire is uniformly wrapped with a layer of BNNSs. Under the action of electric field force, BNNSs are closely combined with silver nanowires, not only covering the nodes with serious heating, but also forming a dense protective film around the silver nanowires, so that the node heat can be quickly dispersed, and the silver nanowires originally exposed to the environment can also be well protected. At the same time, BNNSs are closely and uniformly adhered to silver nanowires, which has good stability and is not easy to be peeled off by external force.

[0064] Figure 3 Figure (a) in the above is the optical transmittance change diagram of the comparative example silver nanowire heater and the heater prepared in Example 1, and Figure (b) is the optical transmittance change diagram of the comparative example Graphene / AgNWs heater. It can be seen from the figure that since the optical transmittance of BNNSs is good, when BNNSs are introduced into the surface of AgNWs by electrodeposition method, the optical transmittance of BNNSs / AgNWs composite film is only slightly reduced compared with the original AgNWs film. The optical transmittance of Graphene / AgNWs composite film is greatly reduced in the visible light range compared with the original film, which is because of the influence of the zero band gap characteristic of graphene.

[0065] Figure 4Figure (a) is the initial SEM morphology of pure AgNWs film, Figure (c) is the initial SEM morphology of BNNSs / AgNWs film of Example 1, Figures (b) and (d) are SEM morphology of pure AgNWs film heater and BNNSs / AgNWs film heater respectively after 10 days of storage in 85℃ humid environment. It can be clearly seen that the pure AgNWs film is severely oxidized in air, the surface of nanowires is covered by oxidation particles, the BNNSs deposited at 12V voltage form uniform coating on the surface of silver nanowires, and only a small amount of oxidation particles appear on its surface after 10 days of accelerated aging in high temperature and humid environment, which indicates that the heater has good stability in high temperature and humid environment. According to the time-temperature response curve of Figure 5 It can be seen from the time-temperature response curve that the BNNSs / AgNWs heater has good stability in high temperature and humid environment, and its steady-state temperature only decreases by about 3℃. The performance of the pure AgNWs heater is severely damaged after 10 days of storage in 85℃ high temperature and high humidity environment, and it has failed.

[0066] Figure 6 Figure (a) is the initial SEM morphology of pure AgNWs film, Figure (c) is the initial SEM morphology of BNNSs / AgNWs film of Example 1, Figures (b) and (d) are SEM morphology of pure AgNWs film heater and BNNSs / AgNWs film heater respectively after 10 days of storage in 85℃ humid environment. It can be clearly seen that the pure AgNWs film is severely oxidized in air, the surface of nanowires is covered by oxidation particles, the BNNSs deposited at 12V voltage form uniform coating on the surface of silver nanowires, and only a small amount of oxidation particles appear on its surface after 10 days of accelerated aging in high temperature and humid environment, which indicates that the heater has good stability in high temperature and humid environment. According to the time-temperature response curve of

[0067] Figure 7are optical transmittance diagrams of the heater obtained under different applied voltages, wherein the absorption peak at 350 nm is the ultraviolet absorption peak of 30 nm silver nanowires. Overall, although the SEM characterization shows that the thickness of the BNNSs changes significantly, the decrease of the optical transmittance of the BNNSs with the increase of the deposition voltage is small, and especially when the deposition voltage is less than 12 V, the decrease of the optical transmittance is very small, which fully embodies the advantage of the BNNSs as a wide band gap material. Compared with graphene, the BNNSs deposited on the substrate have less influence on the light transmittance of the device, and have obvious advantages.

[0068] The BNNSs / metal mesh laminated transparent heater prepared by the application has good heat distribution uniformity, stability, light transmittance and strong water and oxygen isolation ability in a high-temperature and humid environment. The heater can be widely applied to the industrial fields of screens, electrodes, glasses, electronic curtains, windows, lampshades, flexible electronic skins and the like.

[0069] The above examples are the preferred embodiments of the application, but the embodiments of the application are not limited by the above examples, and any changes, modifications, substitutions, combinations and simplifications made without departing from the spirit and principles of the application shall be equivalent replacement modes and shall be included in the protection scope of the application.

Claims

1. A method for preparing a BNNSs / metal mesh laminated transparent heater, characterized in that, The method comprises the following steps: The hexagonal boron nitride powder is mixed with deionized water and subjected to water bath ultrasonic treatment, and then centrifuged to obtain a hexagonal boron nitride nanosheet dispersion solution by taking the upper solution. The metal nanowire solution is laid on the transparent substrate to obtain a metal nanowire transparent substrate after drying, the metal nanowire transparent substrate being composed of a transparent substrate and a metal nanowire grid layer on the transparent substrate; An electrode material is coated on the edge of the metal nanowire transparent substrate, and a metal nanowire grid transparent substrate is obtained after low-temperature drying. The hexagonal boron nitride nanosheet is deposited on the metal nanowire grid transparent substrate by an electrophoretic deposition process, so that the hexagonal boron nitride nanosheet wraps the metal nanowire grid layer, and the BNNSs / metal grid laminated transparent heater is obtained after low-temperature drying.

2. The production method according to claim 1, characterized by, The mass-volume ratio of the hexagonal boron nitride powder to deionized water is (40-50) mg:(20-25) ml; in the electrophoretic deposition process, the metal nanowire grid transparent substrate is used as a cathode, the deposition voltage is 10-20 V, and the deposition time is 10-25 min.

3. The production method according to claim 1 or 2, characterized by, The metal nanowire solution is selected from gold, silver or copper nanowire solution, the water bath ultrasonic treatment time is not less than 8 h, the centrifugal speed is 3000-3500 r / min, and the centrifugal time is 5-30 min.

4. The production method according to claim 3, characterized by, The metal nanowire solution is selected from silver nanowire solution.

5. The production method according to claim 2, characterized by, The deposition voltage is 10-16 V, and the deposition time is 20-25 min.

6. The production method according to claim 4 or 5, characterized by, The metal nanowire solution is laid on the transparent substrate by spin coating, drop coating, spraying or Meyer rod method.

7. A BNNSs / metal mesh laminated transparent heater, characterized in that, The laminated transparent heater comprises a transparent substrate, a metal nanowire grid layer laid on the surface of the transparent substrate, an electrode material arranged at the edge of the metal nanowire grid layer, and a hexagonal boron nitride nanosheet layer wrapping the metal nanowire grid layer. The hexagonal boron nitride powder is mixed with deionized water and subjected to water bath ultrasonic treatment, and then centrifuged to obtain a hexagonal boron nitride nanosheet dispersion solution by taking the upper solution, and the hexagonal boron nitride nanosheet is deposited on the metal nanowire grid layer by an electrophoretic deposition process, so that the hexagonal boron nitride nanosheet wraps the metal nanowire grid layer.

8. The transparent heater according to claim 7, characterized in that, The material of the metal nanowire grid is selected from gold, silver or copper.

9. The transparent heater according to claim 7 or 8, characterized in that The optical transmittance of the laminated transparent heater is within 5% compared with that of a pure metal grid transparent heater corresponding to the laminated transparent heater.

10. The application of the BNNSs / metal grid laminated transparent heater of any one of claims 7 to 9 in the field of screens, electrodes, glasses, electronic curtains, windows, lampshades and flexible electronic skins.

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